Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

The present disclosure provides a method, a terminal, and a gateway for
transmitting IPv6 packets in an IPv4 network. An IPv6 terminal obtains an
IPv6 address of the terminal, where the IPv6 address comprises an IPv4
address, the IPv4 address is an IPv4 address of a gateway or an IPv4
address designated by the gateway, the gateway is a device connecting an
IPv6 network to an IPv4 network, or a device connecting a layer 2 network
to an IPv4 network, multiple IPv6 terminals are connected to the gateway,
and IPv6 addresses of all the IPv6 terminals connected to the gateway
comprise the same IPv4 address; and sends an IPv6 packet to the gateway,
where the IPv6 packet comprises the IPv6 address as a source address. In
embodiments of the present disclosure, traversal of IPv6 packets through
an IPv4 network can be implemented, and IPv4 address resources can be
saved.

Claims:

1. A method for transmitting an IPv6 packet in an IPv4 network,
comprising: obtaining, by an IPv6 terminal, an IPv6 address of the
terminal, wherein the IPv6 address comprises one of an IPv4 address of a
gateway and an IPv4 address designated by the gateway, the gateway is one
of a device connecting an IPv6 network to an IPv4 network and a device
connecting a layer 2 network to an IPv4 network, multiple IPv6 terminals
are connected to the gateway, and IPv6 addresses of all the IPv6
terminals connected to the gateway comprise the same IPv4 address; and
sending, by the IPv6 terminal, an IPv6 packet to the gateway, wherein the
IPv6 packet comprises the IPv6 address as a source address.

2. The method according to claim 1, wherein the IPv4 address of the
gateway is a compressed IPv4 address.

3. The method according to claim 2, wherein the IPv6 address further
comprises a specific field value used to indicate that the IPv6 address
comprises an IPv4 address.

4. A method for transmitting an IPv6 packet in an IPv4 network,
comprising: receiving, by a first gateway, an IPv6 packet sent by an IPv6
terminal, wherein the IPv6 packet comprises a destination IPv6 address;
and if the destination IPv6 address comprises an IPv4 address,
encapsulating, by the first gateway, the IPv6 packet in an IPv4 packet of
which a destination address is the IPv4 address, and sending the IPv4
packet to a second gateway, wherein the IPv4 address comprises one of an
IPv4 address of the second gateway and an IPv4 address designated by the
second gateway, the second gateway is one of a device connecting an IPv6
network to an IPv4 network and a device connecting a layer 2 network to
an IPv4 network, and IPv6 addresses of all IPv6 terminals connected to
the second gateway comprise the same IPv4 address.

5. The method according to claim 4, wherein if the IPv4 address is a
compressed IPv4 address, the encapsulating, by the first gateway, the
IPv6 packet in an IPv4 packet of which a destination address is the IPv4
address comprises: recovering, by the first gateway, the compressed IPv4
address, and encapsulating the IPv6 packet in an IPv4 packet of which a
destination address is the recovered IPv4 address.

6. The method according to claim 5, further comprising: according to a
specific field value that is comprised in the destination IPv6 address
and used to indicate that the destination IPv6 address comprises an IPv4
address, determining, by the first gateway, that the destination IPv6
address comprises an IPv4 address.

7. The method according to claim 4, further comprising: if the
destination IPv6 address does not comprise an IPv4 address,
encapsulating, by the first gateway, the IPv6 packet in an IPv4 packet,
wherein a destination IPv4 address of the IPv4 packet is an IPv4 address
of a specific gateway.

8. The method according to claim 7, further comprising: setting, by the
first gateway, a protocol type in a header of the IPv4 packet to a
specific value, to identify that an IPv6 packet is encapsulated in the
IPv4 packet.

9. A terminal having a processor, comprising: an obtaining module,
configured to obtain, in the processor, an IPv6 address of the terminal,
wherein the IPv6 address comprises one of an IPv4 address of a gateway
and an IPv4 address designated by the gateway, the gateway is one of a
device connecting an IPv6 network to an IPv4 network and a device
connecting a layer 2 network to an IPv4 network, multiple IPv6 terminals
are connected to the gateway, and IPv6 addresses of all the IPv6
terminals connected to the gateway comprise the same IPv4 address; and a
sending module, configured to send, by the processor, an IPv6 packet to
the gateway, wherein an IPv6 packet comprises the IPv6 address as a
source address.

10. The method according to claim 9, wherein the IPv4 address of the
gateway is a compressed IPv4 address.

11. The terminal according to claim 10, wherein the IPv6 address obtained
by the obtaining module further comprises a specific field value used to
indicate that the IPv6 address comprises an IPv4 address.

12. A gateway having a processor, comprising: a receiving module,
configured to receive, in the processor, an IPv6 packet sent by an IPv6
terminal, wherein the IPv6 packet comprises a destination IPv6 address;
and a first encapsulating module, configured to, if the destination IPv6
address comprises an IPv4 address, encapsulate the IPv6 packet in an IPv4
packet of which a destination address is the IPv4 address, and send the
IPv4 packet to a second gateway, wherein the IPv4 address comprises one
of an IPv4 address of the second gateway and an IPv4 address designated
by the second gateway, the second gateway is one of a device connecting
an IPv6 network to an IPv4 network and a device connecting a layer 2
network to an IPv4 network, and IPv6 addresses of all IPv6 terminals
connected to the second gateway comprise the same IPv4 address.

13. The gateway according to claim 12, wherein the first encapsulating
module is configured to, if the destination IPv6 address comprises an
IPv4 address, and the IPv4 address in the IPv6 packet received by the
receiving module is a compressed IPv4 address, recover the compressed
IPv4 address, and encapsulate the IPv6 packet in an IPv4 packet of which
a destination address is the recovered IPv4 address.

14. The gateway according to claim 13, further comprising: a determining
module, configured to, according to a specific field value that is
comprised in the destination IPv6 address and used to indicate that the
destination IPv6 address comprises an IPv4 address, determine that the
destination IPv6 address comprises an IPv4 address.

15. The gateway according to claim 12, further comprising: a second
encapsulating module, configured to, if the destination IPv6 address does
not comprise an IPv4 address, encapsulate the IPv6 packet in an IPv4
packet, wherein a destination IPv4 address of the IPv4 packet is an IPv4
address of a specific gateway.

16. The gateway according to claim 15, wherein the first encapsulating
module is further configured to set a protocol type in a header of the
IPv4 packet to a specific value, to identify that an IPv6 packet is
encapsulated in the IPv4 packet.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No.
PCT/CN2011/074823, filed on May 28, 2011, which claims priority to
Chinese Patent Application No. CN 201010508123.8, filed with the Chinese
Patent Office on Oct. 9, 2010, and Chinese Patent Application No. CN
201010547912.2, filed with the Chinese Patent Office on Nov. 17, 2010,
all of which are incorporated herein by reference in their entireties.

FIELD

[0002] The present disclosure relates to network communications
technologies, and in particular, to a method, a terminal, and a gateway
for transmitting an IPv6 packet in an IPv4 network.

BACKGROUND

[0003] Because IPv4 addresses will be exhausted soon, operators need to
switch their networks and subscribers to IPv6. If an existing network
used to support an IPv4 service is upgraded to support IPv6, the
investment will be too large and an unpredictable problem may arise due
to the network upgrade. Therefore, a mechanism is needed to provide an
IPv6 service in an existing IPv4 network. In an existing solution for
traversal of an IPv6 packet through an IPv4 network, each IPv6 address
corresponds to one IPv4 address, which cannot solve a problem of IPv4
address shortage.

SUMMARY

[0004] Embodiments of the present disclosure provides a method, a
terminal, and a gateway for transmitting an IPv6 packet in an IPv4
network, so as to implement traversal of the IPv6 packet through the IPv4
network and save IPv4 addresses.

[0005] In a first aspect, an embodiment of the present disclosure provides
a method for transmitting an IPv6 packet in an IPv4 network. In the
method, an IPv6 terminal obtains an IPv6 address of the terminal, where
the IPv6 address includes an IPv4 address. The IPv4 address includes an
IPv4 address of a gateway or an IPv4 address designated by the gateway.
The gateway is a device connecting an IPv6 network to an IPv4 network, or
a device connecting a layer 2 network to an IPv4 network. Multiple IPv6
terminals are connected to the gateway. IPv6 addresses of all the IPv6
terminals connected to the gateway include the same IPv4 address. The
IPv6 terminal sends an IPv6 packet to the gateway, where IPv6 packet
includes the IPv6 address as a source address.

[0006] In a second aspect, an embodiment of the present disclosure
provides a method for transmitting an IPv6 packet in an IPv4 network. In
the method, a first gateway receives an IPv6 packet sent by an IPv6
terminal, where the IPv6 packet includes a destination IPv6 address. If
the destination IPv6 address includes an IPv4 address, the first gateway
encapsulates the IPv6 packet in an IPv4 packet of which a destination
address is the IPv4 address, and sends the IPv4 packet to a second
gateway. The IPv4 address included in the destination IPv6 address
includes an IPv4 address of the second gateway or an IPv4 address
designated by the second gateway. The second gateway is a device
connecting an IPv6 network to an IPv4 network, or a device connecting a
layer 2 network to an IPv4 network. IPv6 addresses of all IPv6 terminals
connected to the second gateway include the same IPv4 address.

[0007] In a third aspect, an embodiment of the present disclosure provides
a terminal having a processor. The terminal includes: an obtaining
module, configured to obtain, in the processor, an IPv6 address of the
terminal, where the IPv6 address includes an IPv4 address, the IPv4
address is an IPv4 address of a gateway or an IPv4 address designated by
the gateway, the gateway is a device connecting an IPv6 network to an
IPv4 network, or a device connecting a layer 2 network to an IPv4
network, multiple IPv6 terminals are connected to the gateway, and IPv6
addresses of all the IPv6 terminals connected to the gateway include the
same IPv4 address; and a sending module, configured to send, by the
processor, an IPv6 packet to the gateway, where the IPv6 packet includes
the IPv6 address as a source address.

[0008] In a fourth aspect, an embodiment of the present disclosure
provides a gateway having a processor. The gateway includes: a receiving
module, configured to receive an IPv6 packet sent by an IPv6 terminal,
where the IPv6 packet includes a destination IPv6 address; and a first
encapsulating module, configured to, if the destination IPv6 address
includes an IPv4 address, encapsulate the IPv6 packet in an IPv4 packet
of which a destination address is the IPv4 address, and send the IPv4
packet to a second gateway, where the IPv4 address included in the
destination IPv6 address is an IPv4 address of the second gateway or an
IPv4 address designated by the second gateway, the second gateway is a
device connecting an IPv6 network to an IPv4 network, or a device
connecting a layer 2 network to an IPv4 network, and IPv6 addresses of
all IPv6 terminals connected to the second gateway include the same IPv4
address.

[0009] From the foregoing solutions, it can be known that, in the method
and device for transmitting the IPv6 packet in the IPv4 network according
to the embodiments of the present disclosure, by encapsulating the IPv6
packet in the IPv4 packet, the traversal of the IPv6 packet through the
IPv4 network can be implemented, and an IPv4 address of a gateway
corresponding to multiple IPv6 terminals is used as a destination address
of the IPv4 packet after encapsulation, which may make the multiple IPv6
terminals correspond to the same IPv4 address, to save IPv4 addresses.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] To illustrate solutions in embodiments of the present disclosure
more clearly, accompanying drawings to be used for describing the
embodiments are introduced briefly in the following. Apparently, the
accompanying drawings in the following description are some embodiments
of the present disclosure, and persons of ordinary skill in the art can
further obtain other drawings according to these accompanying drawings
without making creative efforts.

[0011] FIG. 1 is a schematic flowchart of a method according to a first
embodiment of the present disclosure;

[0012] FIG. 2 is a schematic flowchart of a method according to a second
embodiment of the present disclosure;

[0013] FIG. 3a is a schematic diagram of a format of an IPv6 address
according to an embodiment of the present disclosure;

[0014] FIG. 3b is a schematic diagram of another format of an IPv6 address
according to an embodiment of the present disclosure;

[0015]FIG. 4 is a schematic flowchart of a method according to a third
embodiment of the present disclosure;

[0016] FIG. 5 is a schematic structural diagram corresponding to the third
embodiment of the present disclosure;

[0017]FIG. 6 is a schematic flowchart of a method according to a fourth
embodiment of the present disclosure;

[0018]FIG. 7 is a schematic structural diagram corresponding to the
fourth embodiment of the present disclosure;

[0019] FIG. 8 is a schematic structural diagram of a terminal according to
a fifth embodiment of the present disclosure; and

[0020] FIG. 9 is a schematic structural diagram of a gateway according to
a sixth embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make objectives, solutions, and advantages of embodiments of the
present disclosure clearer, the solutions in the embodiments of the
present disclosure are described below with reference to accompanying
drawings in the embodiments of the present disclosure. Apparently, the
described embodiments are merely part rather than all of the embodiments
of the present disclosure. All other embodiments obtained by persons of
ordinary skill in the art without creative effort based on the
embodiments of the present disclosure fall within the protection scope of
the present disclosure.

[0022] FIG. 1 is a schematic flowchart of a method according to a first
embodiment of the present disclosure, including:

[0023] Step 11: An IPv6 terminal obtains an IPv6 address of the terminal,
where the IPv6 address includes an IPv4 address, the IPv4 address is an
IPv4 address of a gateway or an IPv4 address designated by the gateway,
the gateway is a device connecting an IPv6 network to an IPv4 network, or
a device connecting a layer 2 network to an IPv4 network, multiple IPv6
terminals are connected to the gateway, and IPv6 addresses of all the
IPv6 terminals connected to the gateway include the same IPv4 address.

[0024] Optionally, the IPv4 address of the gateway may be a compressed
IPv4 address. For example, IPv4 addresses which can be assigned by a same
operator usually have a same prefix, the foregoing same prefix may be
omitted in the IPv4 address that is included in the IPv6 address and is
of the gateway or designated by the gateway, that is, the IPv6 address
includes a compressed IPv4 address. Because the compressed IPv4 address
is always in one-to-one correspondence with an IPv4 address of a gateway
in an operator network, the compressed IPv4 address may be used as the
IPv4 address of the gateway.

[0025] Optionally, to identify that the IPv6 address includes an IPv4
address, a specific field in the IPv6 address may be set to a specific
value and then indicate that the IPv6 address includes an IPv4 address,
that is, the IPv6 address further includes a specific field value used to
indicate that the IPv6 address includes an IPv4 address.

[0026] The IPv4 address may be included in the first 64 bits of the IPv6
address, that is, a prefix (prefix) part of the IPv6 address. The IPv4
address may also be included in the last 64 bits of the IPv6 address,
that is, a link address part of the IPv6 address.

[0027] Step 12: The IPv6 terminal sends an IPv6 packet to the gateway,
where the IPv6 packet includes the IPv6 address as a source address.

[0028] In this embodiment, the IPv6 address includes the IPv4 address, so
the IPv6 packet can be encapsulated in the IPv4 packet when traversing an
IPv4 network, to implement traversal of the IPv6 packet through the IPv4
network; and multiple IPv6 terminals correspond to one IPv4 address,
which can save IPv4 address resources.

[0029] FIG. 2 is a schematic flowchart of a method according to a second
embodiment of the present disclosure, including:

[0030] Step 21: A first gateway receives an IPv6 packet sent by an IPv6
terminal, where the IPv6 packet includes a destination IPv6 address.

[0031] Step 22: If the destination IPv6 address includes an IPv4 address,
the first gateway encapsulates the IPv6 packet in an IPv4 packet of which
a destination address is the IPv4 address, and sends the IPv4 packet to a
second gateway, where the IPv4 address included in the destination IPv6
address is an IPv4 address of the second gateway or an IPv4 address
designated by the second gateway, the second gateway is a device
connecting an IPv6 network to an IPv4 network, or a device connecting a
layer 2 network to an IPv4 network, and IPv6 addresses of all IPv6
terminals connected to the second gateway include the same IPv4 address.

[0032] Optionally, if the IPv4 address of the gateway or designated by the
gateway may be a compressed IPv4 address, when the first gateway
encapsulates the IPv6 packet in the IPv4 packet of which the destination
address is the IPv4 address, the first gateway first recovers the
compressed IPv4 address, and then encapsulates the IPv6 packet in an IPv4
packet of which a destination address is the recovered IPv4 address. For
example, IPv4 addresses which can be assigned by a same operator usually
have a same prefix, and the foregoing same prefix may be omitted in the
IPv4 address that is included in the IPv6 address and is of the gateway
or designated by the gateway. The first gateway adds the omitted part,
that is, the foregoing same prefix, before the IPv4 address to obtain the
recovered IPv4 address.

[0033] Optionally, the first gateway may judge, according to whether the
destination IPv6 address includes a related indication, whether an IPv4
address is included, that is, if the destination IPv6 address includes a
specific field value which is used to indicate that the destination IPv6
address includes an IPv4 address, the first gateway judges that the
destination IPv6 address includes an IPv4 address.

[0034] In addition, this embodiment may further include that: if the
destination IPv6 address does not include an IPv4 address, the first
gateway encapsulates the IPv6 packet in an IPv4 packet, where a
destination IPv4 address of the IPv4 packet is an IPv4 address of a
specific gateway.

[0035] To enable the second gateway to perform decapsulation correctly,
this embodiment further includes that: the first gateway sets a protocol
type in a header of the IPv4 packet to a specific value to identify that
an IPv6 packet is encapsulated in the IPv4 packet.

[0036] The IPv4 address may be included in the first 64 bits of the IPv6
address. In addition, the IPv4 address may also be included in the last
64 bits of the IPv6 address.

[0037] In this embodiment, by encapsulating the IPv6 packet in the IPv4
packet, traversal of the IPv6 packet through an IPv4 network can be
implemented, and an IPv4 address of a gateway corresponding to multiple
IPv6 terminals is used as a destination address of an IPv4 packet after
encapsulation, which may make the multiple IPv6 terminals correspond to
the same IPv4 address, to save IPv4 addresses.

[0038] In the embodiment of the present disclosure, to make the IPv6
packet traverse the IPv4 network, the assignment of the IPv6 address
needs to be improved, so that the IPv6 address includes an IPv4 address,
and the IPv4 address corresponds to multiple IPv6 terminals. For example,
an IPv6 address shown in FIG. 3a may be assigned in a PPPoE process or a
dynamic host configuration protocol (Dynamic Host Configuration Protocol,
DHCP) process.

[0039] FIG. 3a is a schematic diagram of a format of an IPv6 address
according to an embodiment of the present disclosure. Referring to FIG.
3a, the IPv6 address includes: an identification part occupying 3 bits
(which is specifically 001), a prefix part occupying 61 bits, and a link
address (link address) part occupying 64 bits. In the embodiment of the
present disclosure, the prefix part includes a global routing prefix and
a subnet ID of a terminal. Routing hierarchy may be achieved by using
global routing and the subnet ID, for example, it may be set that the
first 24 bits of the prefix part represent a country, the following 10
bits represent a city, and other bits represent a cell, so as to achieve
a multi-level address. The link address part may include an IPv4 address,
for example, the middle 32 bits of the link address are used to carry the
IPv4 address. In addition, the first n bits of the link address are used
as an identifier (Identifier), to indicate that the IPv6 address includes
an IPv4 address. The remaining 32-n bits of the link address are used to
represent a terminal ID to differentiate different terminals
corresponding to the same IPv4 address.

[0040] Definitely, it can be understood that, in FIG. 3a, a position where
the IPv4 address is included is not limited to the foregoing position of
the link address part, and the IPv4 address may be included in another
position of the link address part. In addition, the position is not
limited to the link address part, and the IPv4 address may also be
included in another part of the IPv6 address.

[0041] For example, the position of the IPv4 address may be at the prefix
part of the IPv6 address.

[0042] FIG. 3b is a schematic diagram of another format of an IPv6 address
according to an embodiment of the present disclosure. The IPv6 address
includes: an identification part occupying 3 bits (which is specifically
001), a prefix part occupying 61 bits, and a link address (link address)
part occupying 64 bits. In the embodiment of the present disclosure, the
prefix part includes an address prefix assigned by an operator, a
compressed IPv4 address, and a subnet ID.

[0043] An improved solution for the IPv6 address has been described above,
and a procedure that an IPv6 packet traverses an IPv4 network will be
described in the following.

[0044]FIG. 4 is a schematic flowchart of a method according to a third
embodiment of the present disclosure, and FIG. 5 is a schematic
structural diagram corresponding to the third embodiment of the present
disclosure. Referring to FIG. 5, a first terminal 51, a first gateway 52,
a second gateway 53, and a second terminal 54 are included, where both
the first terminal 51 and the second terminal 54 are IPv6 terminals, of
which corresponding addresses are IPv6 addresses in the format shown in
FIG. 3a. What is between the first gateway 52 and the second gateway 53
is an IPv4 network. What is between the first terminal 51 and the first
gateway 52 may be an IPv6 network or a layer 2 network, and what is
between the second gateway 53 and the second terminal 54 may be an IPv6
network or a layer 2 network. In this embodiment, an example where the
first terminal 51 sends an IPv6 packet to the second terminal 54 is used.
Referring to FIG. 4, this embodiment includes:

[0045] Step 41: The first terminal sends an IPv6 packet to the first
gateway.

[0046] If what is between the first terminal and the first gateway is an
IPv6 network, the first terminal may send the IPv6 packet to the first
gateway; if what is between the first terminal and the first gateway is a
layer 2 network, because the layer 2 network doesn't care an upper layer
protocol, the first terminal may send the IPv6 packet to the first
gateway as well.

[0047] In FIG. 5, an example where the second gateway is connected to one
second terminal is used. However, in actual implementation, the second
gateway may be connected to multiple second terminals, where all IPv6
addresses of the multiple second terminals include an IPv4 address of the
second gateway. When the second gateway is connected to multiple second
terminals and the first terminal needs to send an IPv6 packet to any one
of the multiple second terminals, a destination IPv6 address of the IPv6
packet includes the IPv4 address of the second gateway. Definitely, an
IPv4 address included in an IPv6 address is not limited to an IPv4
address of a gateway, and may be a public network IPv4 address designated
by the gateway. In addition, to save IPv4 addresses, the public network
IPv4 address designated by the gateway needs to correspond to multiple
IPv6 terminals, and the gateway has published a route of the designated
IPv4 address in an IPv4 network.

[0048] In the embodiment of the present disclosure, an example where the
IPv4 address is the IPv4 address of the gateway is used.

[0049] Step 42: The first gateway encapsulates the IPv6 packet in an IPv4
packet, where a destination address of the IPv4 packet is the IPv4
address included in the IPv6 address.

[0050] Because what is between the first gateway and the second gateway is
an IPv4 network, and the IPv6 packet cannot be transmitted directly, the
IPv6 packet needs to be encapsulated, and the IPv6 packet may be
encapsulated as a payload in the IPv4 packet. In addition, the IPv4
packet has a source IPv4 address being an IPv4 address of the first
gateway, and the destination IPv4 address being the IPv4 address included
in the IPv6 packet.

[0051] In addition, a value of a protocol type in a header of the IPv4
packet may be set to a specific value, where the specific value indicates
that an IPv6 packet is encapsulated in the IPv4 packet.

[0052] Step 43: The first gateway sends the IPv4 packet to the second
gateway.

[0053] Step 44: The second gateway decapsulates the IPv4 packet to obtain
the IPv6 packet.

[0054] After determining, according to the protocol type in the header of
the IPv4 packet, that an IPv6 packet is encapsulated in the IPv4 packet,
the second gateway decapsulates the IPv4 packet to obtain the IPv6
packet.

[0055] In some cases, for example that the gateway uses, by default, an
encapsulation manner in the embodiment of the present disclosure, the
second gateway may also directly determine that an IPv6 packet is
encapsulated in the IPv4 packet, and decapsulate the IPv4 packet to
obtain the IPv6 packet.

[0056] Step 45: The second gateway sends the second terminal the IPv6
packet obtained through decapsulation.

[0057] In this embodiment, the example where the first terminal sends the
IPv6 packet to the second terminal is used. A similar process may be used
when the second terminal sends an IPv6 packet to the first terminal, and
the only difference is that the first terminal and the second terminal
need to interchange their roles, and the first gateway and the second
gateway need to interchange their roles. For example, when an IPv6 packet
sent by the second terminal is sent to the second gateway, the second
gateway encapsulates the IPv6 packet in an IPv4 packet, where the IPv4
packet has a destination IPv4 address being the IPv4 address of the first
gateway. Further, the second gateway sets a protocol type value of the
IPv4 packet to a specific value, so that the first gateway parses the
received IPv4 packet to obtain the IPv6 packet.

[0058] In this embodiment, by using an IPv4 address of a gateway as a
destination IPv4 address of an IPv4 packet for encapsulating an IPv6
packet, the consumption of IPv4 addresses may not be increased, thereby
saving IPv4 addresses. By setting that terminals under a same gateway
correspond to a same IPv4 address, only a pair of IPv4 routing paths in
the IPv4 network may be needed when the multiple terminals are used as
destination ends, thereby reducing routing overheads. By using an IPv4
address, included in an IPv6 address, as a destination address during
IPv4 packet encapsulation, the establishment and maintenance of a tunnel
may be avoided.

[0059] In the third embodiment, an example of communication between peers
is used, that is, IPv6 addresses of both the first terminal and the
second terminal are in the format shown in FIG. 3a. Communication between
non-peers is described in the following, where non-peer refers to that
one of two communicating terminals does not have the format shown in FIG.
3a.

[0060] The following describes a procedure that an IPv6 packet traverses
an IPv4 network, when an IPv4 address is a compressed IPv4 address.

[0061] The first terminal sends an IPv6 packet to the first gateway.

[0062] If what is between the first terminal and the first gateway is an
IPv6 network, the first terminal may send the IPv6 packet to the first
gateway; if a layer 2 network is provided between the first terminal and
the first gateway, because the layer 2 network doesn't care an upper
layer protocol, the first terminal may also send the IPv6 packet to the
first gateway as well.

[0063] In actual implementation, the second gateway may be connected to
multiple second terminals, where IPv6 addresses of all the multiple
terminals include an IPv4 address of the second gateway, and the IPv4
address of the second gateway is a compressed IPv4 address. When the
second gateway is connected to multiple second terminals and the first
terminal needs to send an IPv6 packet to any one of the multiple second
terminals, a destination IPv6 address of the IPv6 packet includes the
IPv4 address of the second gateway, where with a same part of a same
operator network being omitted, the IPv4 address is a compressed IPv4
address.

[0064] The first gateway encapsulates the IPv6 packet in an IPv4 packet,
where a destination address of the IPv4 packet is the IPv4 address
included in the IPv6 address.

[0065] Because what is between the first gateway and the second gateway is
an IPv4 network, and the IPv6 packet cannot be transmitted directly, the
IPv6 packet needs to be encapsulated, and the IPv6 packet may be
encapsulated as a payload in the IPv4 packet. In addition, the IPv4
packet has a source IPv4 address being an IPv4 address of the first
gateway, and the destination IPv4 address being the IPv4 address included
in the IPv6 packet. Because the IPv4 address included in the IPv6 packet
is a compressed IPv4 address, the first gateway first recovers the
compressed IPv4 address, that is, adds the omitted part to the IPv4
address, to obtain the recovered IPv4 address, where the destination IPv4
address of the IPv4 packet is the recovered IPv4 address.

[0066] In addition, a value of a protocol type in a header of the IPv4
packet may be set to a specific value, where the specific value indicates
that an IPv6 packet is encapsulated in the IPv4 packet.

[0067] Step 43: The first gateway sends the IPv4 packet to the second
gateway.

[0068] Step 44: The second gateway decapsulates the IPv4 packet to obtain
the IPv6 packet.

[0069] The second gateway may determine, according to the protocol type in
the header of the IPv4 packet, that an IPv6 packet is encapsulated in the
IPv4 packet, and decapsulate the IPv4 packet to obtain the IPv6 packet.

[0070] In some cases, for example that the gateway uses, by default, an
encapsulation manner in the embodiment of the present disclosure, the
second gateway may also directly determine that an IPv6 packet is
encapsulated in the IPv4 packet, and decapsulate the IPv4 packet to
obtain the IPv6 packet.

[0071] Step 45: The second gateway sends the second terminal the IPv6
packet obtained through decapsulation.

[0072] In this embodiment, the example where the first terminal sends the
IPv6 packet to the second terminal is used. A similar process may be used
when the second terminal sends an IPv6 packet to the first terminal, and
the only difference is that the first terminal and the second terminal
need to interchange their roles, and the first gateway and the second
gateway need to interchange their roles. For example, when an IPv6 packet
sent by the second terminal is sent to the second gateway, the second
gateway encapsulates the IPv6 packet in an IPv4 packet, where the IPv4
packet has a destination IPv4 address being the IPv4 address of the first
gateway. Further, the second gateway may set a protocol type value of the
IPv4 packet to a specific value, so that the first gateway parses the
received IPv4 packet to obtain the IPv6 packet.

[0073] In this embodiment, by using an IPv4 address of a gateway as a
destination IPv4 address of an IPv4 packet for encapsulating an IPv6
packet, the consumption of IPv4 addresses may not be increased, thereby
saving IPv4 addresses. By setting that terminals under a same gateway
correspond to a same IPv4 address, only a pair of IPv4 routing paths in
the IPv4 network may be needed when the multiple terminals are used as
destination ends, thereby reducing routing overheads. By using an IPv4
address, included in an IPv6 address, as a destination address during
IPv4 packet encapsulation, the establishment and maintenance of a tunnel
may be avoided.

[0074]FIG. 6 is a schematic flowchart of a method according to a fourth
embodiment of the present disclosure, and FIG. 7 is a schematic
structural diagram corresponding to the fourth embodiment of the present
disclosure. Referring to FIG. 7, a first terminal 71, a first gateway 72,
a third gateway 73, and a third terminal 74 are included, where both the
first terminal 71 and the third terminal 74 are IPv6 terminals, of which
corresponding addresses are IPv6 addresses; however, an IPv6 address of
the first terminal 71 is in the format shown in FIG. 3a or FIG. 3b, and
an IPv6 address of the third terminal 74 is not in the format shown in
FIG. 3a or FIG. 3b. What is between the first gateway 72 and the third
gateway 73 is an IPv4 network. What is between the first terminal 71 and
the first gateway 72 may be an IPv6 network or a layer 2 network, and in
this embodiment, an example where what is between the third gateway 73
and the third terminal 74 is an IPv6 network of an ISP other than an
internet service provider (Internet Service Provider, ISP) to which the
first terminal belongs is used. Definitely, the third gateway may also be
another specific gateway corresponding to an IPv6 address which is not in
the format shown in FIG. 3a or FIG. 3b, and is not limited to a gateway
connected to a different ISP. In this embodiment, an example where the
first terminal 71 sends an IPv6 packet to the third terminal 74 is used.
Referring to FIG. 6, this embodiment includes:

[0075] Step 61: The first terminal sends an IPv6 packet to the first
gateway.

[0076] For details, reference may be made to step 41.

[0077] Step 62: The first gateway encapsulates the IPv6 packet in an IPv4
packet, where a destination address of the IPv4 packet is an IPv4 address
of the third gateway.

[0078] In a certain network, a specific gateway may be set, and the
specific gateway may be a gateway between the network and another
network. For example, referring to FIG. 7, because the third gateway
connects the IPv6 network, to which the first gateway belongs, to another
IPv6 network, the third gateway is the specific gateway.

[0079] Therefore, when the first gateway receives an IPv6 packet, and
obtains that an IPv6 address in the IPv6 packet is not in the format
shown in FIG. 3a or FIG. 3b, the IPv6 packet needs to be encapsulated in
an IPv4 packet and then sent to the specific gateway. An IPv4 address of
the specific gateway may be set in the first gateway, so that when the
IPv6 packet is encapsulated, the IPv4 address of the specific gateway is
used as a destination IPv4 address, and an IPv4 address of the first
gateway is used as a source IPv4 address. In this way, the received IPv6
packet is encapsulated by the first gateway and then sent to the specific
gateway.

[0080] In addition, a value of a protocol type in a header of the IPv4
packet may be set to a specific value, where the specific value indicates
that an IPv6 packet is encapsulated in the IPv4 packet.

[0081] Step 63: The first gateway sends the IPv4 packet to the third
gateway.

[0082] Step 64: The third gateway decapsulates the IPv4 packet to obtain
the IPv6 packet.

[0083] After determining, according to the protocol type in the header of
the IPv4 packet, that an IPv6 packet is encapsulated in the IPv4 packet,
the third gateway decapsulates the IPv4 packet to obtain the IPv6 packet.

[0084] Step 65: The third gateway sends the third terminal the IPv6 packet
obtained through decapsulation.

[0085] In this embodiment, the example where the first terminal sends the
IPv6 packet to the third terminal is used. A similar process may be used
when the third terminal sends an IPv6 packet to the first terminal, and
the only difference is that the first terminal and the third terminal
need to interchange their roles, and the first gateway and the third
gateway need to interchange their roles. For example, when an IPv6 packet
sent by the third terminal is sent to the third gateway, the third
gateway encapsulates the IPv6 packet in an IPv4 packet, where the IPv4
packet has a destination IPv4 address being the IPv4 address of the first
gateway, and a source IPv4 address being the IPv4 address of the third
gateway. Further, the third gateway sets a protocol type value of the
IPv4 packet to a specific value, so that the first gateway parses the
received IPv4 packet to obtain the IPv6 packet.

[0086] In this embodiment, by using an IPv4 address of a gateway as a
destination IPv4 address, the consumption of IPv4 addresses may not be
increased, thereby saving IPv4 addresses. By setting that terminals under
a same gateway correspond to a same IPv4 address, only a pair of IPv4
routing paths in the IPv4 network may be needed when the multiple
terminals are used as destination ends, thereby reducing routing
overheads. By using an IPv4 address, included in an IPv6 address, as a
destination address during IPv4 packet encapsulation, the establishment
and maintenance of a tunnel may be avoided.

[0087] FIG. 8 is a schematic structural diagram of a terminal according to
a fifth embodiment of the present disclosure, including: an obtaining
module 81 and a sending module 82. The obtaining module 81 is configured
to obtain an IPv6 address of the terminal, where the IPv6 address
includes an IPv4 address, the IPv4 address is an IPv4 address of a
gateway or an IPv4 address designated by the gateway, the gateway is a
device connecting an IPv6 network to an IPv4 network, or a device
connecting a layer 2 network to an IPv4 network, multiple IPv6 terminals
are connected to the gateway, and IPv6 addresses of all the IPv6
terminals connected to the gateway include the same IPv4 address. The
sending module 82 is configured to send an IPv6 packet to the gateway,
where the IPv6 packet includes the IPv6 address as a source address.

[0088] The IPv4 address of the gateway may be a compressed IPv4 address.

[0089] The IPv6 address obtained by the obtaining module 81 further
includes a specific field value used to indicate that the IPv6 address
includes an IPv4 address.

[0090] The IPv4 address that is included in the IPv6 address obtained by
the obtaining module 81 may be in the first 64 bits of the IPv6 address.
The IPv4 address that is included in the IPv6 address obtained by the
obtaining module 81 may also be in the last 64 bits of the IPv6 address.

[0091] In this embodiment, because the IPv6 address includes the IPv4
address, the IPv6 packet may be encapsulated in the IPv4 packet when
traversing an IPv4 network, so as to implement traversal of the IPv6
packet through the IPv4 network; and because multiple IPv6 terminals
correspond to one IPv4 address, IPv4 address resources can be saved.

[0092] FIG. 9 is a schematic structural diagram of a gateway according to
a sixth embodiment of the present disclosure, including a receiving
module 91 and a first encapsulating module 92. The receiving module 91 is
configured to receive an IPv6 packet sent by an IPv6 terminal, where the
IPv6 packet includes a destination IPv6 address. The first encapsulating
module 92 is configured, if the destination IPv6 address includes an IPv4
address, encapsulate the IPv6 packet in an IPv4 packet of which a
destination address is the IPv4 address, and send the IPv4 packet to a
second gateway, where the IPv4 address included in the destination IPv6
address is an IPv4 address of the second gateway or an IPv4 address
designated by the second gateway, the second gateway is a device
connecting an IPv6 network to an IPv4 network, or a device connecting a
layer 2 network to an IPv4 network, and IPv6 addresses of all IPv6
terminals connected to the second gateway include the same IPv4 address.

[0093] Optionally, the first encapsulating module may be configured to, if
the destination IPv6 address includes an IPv4 address and the IPv4
address in the IPv6 packet received by the receiving module is a
compressed IPv4 address, recover the compressed IPv4 address, and
encapsulate the IPv6 packet in an IPv4 packet of which a destination
address is the recovered IPv4 address.

[0094] Optionally, this embodiment may further include a determining
module 93, where the determining module 93 is configured to, according to
a specific field value that is included in the destination IPv6 address
and used to indicate that the destination IPv6 address includes an IPv4
address, determine that the destination IPv6 address includes an IPv4
address.

[0095] In addition, this embodiment may further include and a second
encapsulating module 94, where the second encapsulating module 94 is
configured to, if the destination IPv6 address does not include an IPv4
address, encapsulate the IPv6 packet in an IPv4 packet, where a
destination IPv4 address of the IPv4 packet is an IPv4 address of a
specific gateway.

[0096] The first encapsulating module 92 may be further configured to set
a protocol type in a header of the IPv4 packet to a specific value, to
identify that an IPv6 packet is encapsulated in the IPv4 packet.

[0097] In this embodiment, by encapsulating the IPv6 packet in the IPv4
packet, traversal of the IPv6 packet through an IPv4 network can be
implemented, and an IPv4 address of a gateway corresponding to multiple
IPv6 terminals is used as a destination address of the IPv4 packet after
encapsulation, which may make the multiple IPv6 terminals correspond to
the same IPv4 address, to save IPv4 addresses.

[0098] It can be understood that, for related features in the foregoing
methods and devices, reference may be made to each other. In addition,
"first" and "second" in the foregoing embodiments are used to
differentiate the embodiments, but do not imply the preference among the
embodiments.

[0099] Persons of ordinary skill in the art can understand that all or
part of the steps in the foregoing method embodiments may be implemented
by a program instructing relevant hardware such as a hardware processor.
The program may be stored in a computer readable storage medium
accessible to the hardware processor. When the program runs, the steps of
the foregoing method embodiments are executed. The storage medium may
include various media capable of storing program codes, such as a ROM, a
RAM, a magnetic disk, or a CD-ROM.

[0100] Finally, it should be noted that the foregoing embodiments are
merely provided for illustrating the solutions of the present disclosure,
but not intended to limit the present disclosure. Although the present
disclosure are illustrated in detail with reference to the embodiments,
persons of ordinary skill in the art should understand that, they still
can make modifications to the solution recorded in each of the
embodiments, or equivalent replacements to some features in the solution;
and such modifications or replacements do not cause the essence of
corresponding solutions to depart from the spirit and scope of the
solutions in each of the embodiments of the present disclosure.